Lighting or surge arrestors are typically connected to power lines to carry electrical surge currents to ground, thereby preventing damage to lines and equipment connected to the arrestors. Arrestors offer high resistance to normal voltage across power lines, but offer very low resistance to surge currents produced by sudden high voltage conditions caused by, for example, lighting strikes, switching surge currents or temporary overvoltages. After the surge, the voltage drops and the arrestor normally returns to a high resistance state. However, upon arrestor malfunction or failure, the high resistance state is not resumed, and the arrestor continues to provide an electrical path from the power line to ground. Ultimately, the line will fail due to a short circuit condition or breakdown of the distribution transformers, and the arrestor will require replacement.
To avoid line failure, disconnector assemblies are commonly used in conjunction with arrestors to separate a malfunctioning arrestor from the circuit and to provide a visual indication of arrestor failure. Conventional disconnector assemblies have an explosive charge to destroy the circuit path and physically separate the electrical terminals. Examples of such disconnector assemblies are disclosed in U.S. Pat. No. 5,952,910 to Krause and U.S. Pat. Nos. 5,057,810 and 5,113,167 to Raudabaugh, as well as U.S. Pat. No. 5,434,550 to Putt and U.S. Pat. No. 4,471,402 to Cunningham, the subject matter of each of which are hereby incorporated by reference.
However, conventional disconnector assemblies have components loaded within the bracket cavity. Adhesive is used to secure the ground terminal within the bracket. Often, the ground terminals become misaligned before the adhesive cures, thereby rendering the disconnector assembly unfit for use.
Additionally, the adhesive may flow into the internal cavity housing the isolator assembly, thereby contaminating the isolator assembly by interfering with the electrical contacts and rendering the disconnector assembly unfit for use. A gasket may be positioned between the ground terminal and the isolator assembly to prevent contamination of the isolator assembly by the adhesive. However, the gasket does not eliminate flow of the adhesive into the bracket cavity.
Furthermore, contamination may adhere to the adhesive, thereby forming an electrical track or path across the adhesive. Such an electrical track lowers the insulation resistance of the arrestor, which renders the arrestor unfit for use as an insulator.
Production of such unfit disconnector assemblies is costly, as well as time consuming. Manufacturing disconnector assemblies requiring extra parts to protect the isolator assembly increases inventory in addition to increasing costs and manufacturing times.
A need exists for an improved disconnector assembly for an arrestor that overcomes the aforementioned problems.
Accordingly, it is a primary objective of the present invention to provide a disconnector assembly for an arrestor having a ground terminal partially disposed in a bore in a cap to reduce the possibility of the ground terminal becoming misaligned during manufacture of the disconnector assembly.
A further objective of the present invention is to provide a disconnector assembly for an arrestor that requires less adhesive for securing the cap to the bracket, thereby reducing both the likelihood of contaminating the isolator assembly and manufacturing costs.
A still further objective of the present invention is to provide a disconnector assembly for an arrestor that having a cap that encapsulates the adhesive, thereby eliminating electrical tracking due to contamination build-up on the adhesive.
The foregoing objects are basically attained by providing an assembly for an arrestor. The assembly has a bracket that has a base and a wall. The wall extends substantially perpendicularly from the base and defines a cavity. An isolator assembly is disposed within the cavity. A cap is connected to the wall remote from the base to close the cavity. A bore extends into the cap from a surface thereof remote from the cavity. A stud is partially disposed in the bore. An adhesive between the cap and the wall secures the cap to the wall.
The stud is partially disposed in the bore in the cap, thereby eliminating misalignment of the stud. Less adhesive is required to secure the cap to the bracket, thereby reducing the likelihood of contaminating the isolator assembly with the adhesive and eliminating the need for a gasket between the cap and the isolator assembly. Since the adhesive is encapsulated by the cap, contamination is not able to form an electrical path across the adhesive, thereby preventing the occurrence of electrical tracking.
Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the invention.